Kinase regulation by sulfur and selenium containing compounds.

Kinases are enzymes that are involved in a wide-range of cellular targets such as cell proliferation, metabolism, survival and apoptosis. Aberrations in the activity of the kinases have been linked to many human diseases such as diabetes, inflammation and cancer. The discovery of more than 518 kinases encoded by the human genome has spurred the development of rapid screening techniques for potential drugs against these enzymes and these have been identified as interesting targets for medicinal chemistry programs, especially in cancer therapy. On the other hand, sulfur and selenium have been increasingly recognized as essential elements in biology and medicine. Converging data from epidemiological and clinical studies have highlighted these elements as effective chemopreventive agents, particularly against various types of cancer (prostate, lung, breast, leukemia, colon, skin, lymphome, thyroid, pancreas, liver). These elements act through a wide range of potential mechanisms where one identified signal pathway event is kinase modulation, which is common for the two elements and emerges as a valid target. The kinases modulated by sulfur and selenium derivatives include MAP, ERK, JNK, Akt, Cdc2, Cyclin B1 and Cdc25c amongst others. Although both of the elements in question are in the same group in the periodic table and have similar biochemistries, there are relevant differences related to redox potentials, stabilities, oxidation states and anticancer activity. Literature data suggest that the replacement of sulfur by selenium in established cancer chemopreventive agents results in more effective chemopreventive analogs. In view of the multi-target kinase mechanisms in preventing cellular transformation, as well as the differences and similarities between them, in this review we focus on the development of new structures that contain selenium and/or sulfur and discuss our understanding of the regulation of antitumoral effects with emphasis on kinase modulation activity and its implications in cancer.